Means for improving the stability of aeroplanes.



H. S. WILDEBLOOD.

MEANS FOR IMP OPLANES APPLICATION FILED APR.17, 1911.

Patented Nov. 11, 1913.

Ink/6121b 553123 )ZiZdebZood. W agaoriacz 5t MEANS FOBIMPROVING THE STABILITY OF .AEBOPLANES.

Specification of Letters Patent.

Patented Nov. 1 1., 191-3.

Application filed April 17, 1911. Serial No. 621,641.

To all whom it may concern:

Be it known that I, HENRY Sermon WILDE- BLoon, of the city of Lucknow, in the Empire of India, have invented a new and useful Means for Improving the Stability of Aeroplanes, of which the following is a specification.

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This invention relates to means for improving the stability of aeroplanes, and con sists in the. constructions, combinations arrangements of parts hereinafter described and claimed.

My invention resides particularly in the provision, on an aeroplane, of stabilizing planes swingingly mounted oneither side of the frame, and adaptedto oppose-the tilting effect due to side air'stream lines; the plane on the windward side tending to lie in'the stream lines, while the plane on the leeward side lying at. an angle of incidence, negative or positive as the case may be, with the stream lines, from which it will be seen thatthe action is entirely automatic and not dependent upon thecontrol of the pilot. It will thus be seen that the vertical component of. the wind pressure-on the plane on the leeward side, due to the side air stream lines, resists the tilting action and tends to right the machine, thus securing automatic lateral stability. If the limit of action on the plane onthe windward side is passed then this plane will also present an angle of incidence to the side stream lines. This angle of incidence will, however, be much smaller than that of the plane on the leeward side, so that the vertical component on this latter plane will be greater than that on the windward side. In this case it will be seen that two vertical components are acting on the machlne, one tending to increase the tilt while the other, much the tends to right the machine.

llndescribing my invention in detail rcference will be had to the accompanying drawings wherein: Figure 1 is a perspective view of an aeroplane provided with my invention and disclosing the stabilizing planes in the upward position. Fig. 2 is a perspective View similar to Fig. 1 and illustrating the stabilizing planes in the lowered position. Fig. 3 is a diagrammatic View disclosing the limit of motion of the stabilizing planes to eitherside of the frame of the machine. Fig. 4 is a diagrammatic view illustrating the principle upon which my invention depends. Fig. 5 is a diagrammatic and view similar to Fig. t, but under more severe conditions. Fig. 6 is a diagrammatic view illustrating the action of side currents upon an aeroplane tilted in a direction opposite to that shown in Figs. 4 and 5. Fig. 7 is a top plan view of an aeroplane equipped with my invention. Fig. 8 is a top plan view of a main plane showm my improved stabilizing plane mergin TI'OII] the sides thereof. Fig. 9 is a top p an view of an aeroplane provided with stabilizing planes formed integral with the main supporting plane; and Fig. 10 is a fragmentary perspective view of a biplane provided with stabilizingplanes.

Referring to Figs. 1 to 6 a shows the main plane, which is made rigid by ribs, stays, etc, in the'usual way. The side members .are carried backward and have mounted thereon planes 7) and 0 by means of their outer edges do and fg. h is a cross member. The planes 6 and c are made from strong, flexible material, suitably attached to the back extensions of the side members. These planes which may be made up of strong aeroplane fabricor canvas and cane or bamboo are left free to move up and down except for their outer edges. To the corners 70 is flexible cords or their equivalents or the like we are attached. The other end of these cords or the like is attached to the framework of the machine and the length of each cord or the like is such that the planes 6 and 0 have a certain limited uncontrolled free movement upward as shown at Figs. 1 and 3 and downward as shown at Figs. 2 and 3. To prevent flapping the leading edges of the planes b and 0 may be secured to the trailing edge of the main plane by a lacing or otherwise at the cost of a slight loss of efficiency near the leading edge.

In Figs. 4, 5, 6 the machine is shown in side air stream lines represented by the arrow n. At Fig. t the machine is'slightly tilted and it will be seen that the windward plane b lies in the stream lines and, therefore, has no vertical component while the leeward plane 0 presents a positive angle of incidence to the side air stream lines, consequently a vertical component 32 results which acts in an upward direction and tends to right the machine. The machine is shown still further tilted in'Fig. 5, and it will be observed that the limit of action of the plane 6 has passed and that this plane presents a small positive angle of incidence to the side air stream lines, resulting in a vertical component 9 tending to still further tilt the machine. The plane 0 is, however, at a larger positiveangle of incidence so that .its vertical component '12 is much greater than 9 and a tendency to right the machine is given which is greater than the tendency to tilt due to the component 9. As the machine rights itself the component 9 gradually lessens until the plane 6 lies in the air stream lines, when it is entirely eliminated.

Referring now to Fig. 6, in this figure the machine is shown tilted in the opposite direction, and the side air stream lines 71. act upon the plane 0 so that it presents a negative angle of incidence and the resulting vertical component 1* as will be observed tends to right the machine, the plane I; lying in the side air stream lines.

It is obvious that these stabilizing planes may be fitted to any form of aeroplane in any required positions and that instead of a cord or the like any suitable means may be employed to enable the inner free edges and the other flexible parts of the planes to move,

without control, upward and downward toa limited extent.

In some cases, the stabilizing planes may be merged into the main plane, care however being taken not to interfere with their free automatic up and down motion. Such an arrangement is shown at Fig. 7, where stiffening of the main plane 8 is stopped at the ribs t so that the portions of the plane at the back lying beyond the ribs 25 have a certain amount of flexibility. In this way rearward extensions u rigidly connected to the backward extensions of the main plane framework at their outer edges in a similar manner to the planes 6 and c in Figs. 1 to 6, take the place of the planes 7) and 0, it being understood that the inner portions of the extensions 21, are entirely free, flexible, and uncontrolled, the corners a limiting the movement by being connected to cords or the like in a manner previously explained. Another of these arrangements is shown in Fig. 8 where the plane to has only a stiffened outer and forward edge :0. This plane is flexible except for its fixed edge and its flexibility is so adjusted by bamboo or cane and cross lines of lacing or otherwise that the necessary degree of flexibility is given to its central and trailing portions respectively. The flexible, horn like, trailing portions 2 have a limited independent up and down movement to enable them to act like the planes Z) and c in Figs. 1 to 6. I may make these portions incline slightly upward by bending their outer edges or I may make the latter flexible or movable if desired.

Fig. 9 shows plan of an aeroplane in which 2 represents the main plane, behind which are mounted a pair of planes (1 and Z) in a manner previously explained.

The corner of a biplane shown at Fig. 10 has mounted behind its main planes the trailing planes a having their action limited as described above.

I claim:

1. In an aeroplane, the combination with a frame, and a supporting plane carried by said frame, of stabilizing planes secured at their outer edges along the side rails of the frame to swing inwardly of said frame at each side thereof, and means for limiting said stabilizing planes to swing within an acute angle with reference to the plane of said frame.

2. In an aeroplane, the combination with a frame, and a supporting plane mounted at the forward portion of said frame, of stabilizing planes merging rearwardly from said supporting plane at each side thereof, having their outer edges secured to the side rails of said,frame, and leaving the inner edges free whereby said planes may describe an acute angle to either side of the plane of said frame.

8. In an aeroplane, the combination with a frame, and a supporting plane carried by said frame, of automatic-adjusting stabilizing planes mounted at their outer edges along the side rails of the frame to swing within an acute angle to either side of the plane of said frame, the windward plane adapted to adjust itself to lie in the side stream line and have no vertical component, the leeward plane presenting an angle of incidence to the stream line and resolving the force of the latter into a Vertical com-.

ponent adapted to assist in righting the aeroplane.

4. In an aeroplane, the combination with a frame, and a supporting plane carried by said frame, of means for assisting to return said aeroplane from a condition of tilt produced bylateral air currents comprising a windward and a leeward plane, each secured at its outer longitudinal edge along the side rails of the frame to swing Within said frame, said windward plane adapted to adjust itself to lie in the stream line and have no vertical component, said leeward plane presenting an angle of incidence to the stream line and resolving the force of the latter into a vertical component adapted to assist in righting the aeroplane, and means for limiting said stabilizing planes to swing within an acute angle with reference to the plane of the frame.

HENRY SEDDON WILDEBLOOD. Witnesses:

' LALIT CHARAN DATTA,

JonN PAUL Manors. 

